umm... in the last answer i forgot to put + C , put the + C depends on your teacher since if the teacher is telling you to find the antiderivative, there is no need to add a C in there. Of course, if you are looking for an indefinite integral, +C is necessary. There is some confusion in the +C thing, so i didn't put it in there.

First, congrats! Though you're just a 10th grade student, you know how to solve integrals.

Yes, it is more easier to solve by substituting sin x, but this method was already indicated in the first answer and I've only provided another way to solve this integral, because this is the basic ideea of providing more answers to a question.